package com.qlm.tools;
 
import java.io.UnsupportedEncodingException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
 
public class MD5Utils {
    public static void main(String[] args){
        System.out.println(getMd5String("123456"));
        System.out.println(MD5("good"));
    }
     
     
    public final static String MD5(String s) {
        char hexDigits[] = { '0', '1', '2', '3', '4',
                             '5', '6', '7', '8', '9',
                             'A', 'B', 'C', 'D', 'E', 'F' };
        try {
            byte[] btInput = s.getBytes();
     //获得MD5摘要算法的 MessageDigest 对象
            MessageDigest mdInst = MessageDigest.getInstance("MD5");
     //使用指定的字节更新摘要
            mdInst.update(btInput);
     //获得密文
            byte[] md = mdInst.digest();
     //把密文转换成十六进制的字符串形式
            int j = md.length;
            char str[] = new char[j * 2];
            int k = 0;
            for (int i = 0; i < j; i++) {
                byte byte0 = md[i];
                str[k++] = hexDigits[byte0 >>> 4 & 0xf];
                str[k++] = hexDigits[byte0 & 0xf];
            }
            return new String(str);
        }
        catch (Exception e) {
            e.printStackTrace();
            return null;
        }
    }
     
     
     
    public static String getMd5String(String str){
        MessageDigest messageDigest = null;  
           
        try {  
            messageDigest = MessageDigest.getInstance("MD5");  
     
            messageDigest.reset();  
     
            messageDigest.update(str.getBytes("UTF-8"));  
        } catch (NoSuchAlgorithmException e) {  
            System.out.println("NoSuchAlgorithmException caught!");  
            System.exit(-1);  
        } catch (UnsupportedEncodingException e) {  
            e.printStackTrace();  
        }  
     
        byte[] byteArray = messageDigest.digest();  
     
        StringBuffer md5StrBuff = new StringBuffer();  
     
        for (int i = 0; i < byteArray.length; i++) {              
            if (Integer.toHexString(0xFF & byteArray[i]).length() == 1)  
                md5StrBuff.append("0").append(Integer.toHexString(0xFF & byteArray[i]));  
            else 
                md5StrBuff.append(Integer.toHexString(0xFF & byteArray[i]));  
        }  
     
        return md5StrBuff.toString();  
    }
    
}
